Siemens SITRANS L Operating Instructions Manual page 82

Remote operation
7.1 Operating via AMS Device Manager
Sampling
[see Sampling (2.5.8.)]
• Echo Lock [see Echo Lock (2.5.8.1.)]
• Sampling Up [see Up Sampling (2.5.8.2.)]
• Sampling Down [see Down Sampling (2.5.8.3.)]
Echo Quality
[see Echo Quality (2.5.9.)]
• Confidence [see Confidence (2.5.9.1.)]
• Echo Strength [see Echo Strength (2.5.9.2.)]
• Noise Average
Displays the average ambient noise (in dB above 1 μV rms) of a noise profile. Noise level is
a combination of transient noise and receiving circuitry. After a measurement, the values
from the previous noise shot will be displayed.
TVT (time varying threshold)
A time-varying curve that determines the threshold level above which echoes are determined
to be valid.
Modify the TVT to screen out false echoes [see Time Varying Threshold (TVT) (Page 234), and
Auto False Echo Suppression (2.5.10.1.)].
Navigate to Configure/Setup > LTB > Setup > Signal Processing and click on TVT. Click on
one of the two tabs to access the parameters listed:
TVT Setup
• Auto False Echo Suppression [see Auto False Echo Suppression (2.5.10.1.)]
• Auto False Echo Suppression Range [see Auto False Echo Suppression Range
(2.5.10.2.)]
• Hover Level [see Hover Level (2.5.10.3.)]
• Shaper Mode [see Shaper Mode (2.5.10.4.)]
Auto False Echo Suppression
1. Determine Auto False Echo Suppression Range. Measure the actual distance from the sensor
reference point to the material surface using a rope or tape measure.
2. Subtract 0.5 m (20") from this distance, and use the resulting value.
3. Open the menu Configure/Setup > LTB > Setup > Signal Processing > TVT and set Auto
False Echo Suppression Range.
4. From the same menu, set Auto False Echo Suppression to learn. The device will
automatically revert to On (Use Learned TVT) after a few seconds.
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SITRANS LR250 with FOUNDATION FIELDBUS
Operating Instructions, 09/2021, A5E32221411-AH